1. Field of the Invention
The present invention relates generally to a device for adjustment of a trunnion, and more particularly relates to a device to adjust the heel of a table saw blade.
2. Description of Related Art
Various table saws for woodworking and the like are known and commercially available. A typical bench or floor-model table saw consists of a main chassis supporting a substantially flat, stationary work surface. The work surface is provided with a slot for the saw blade and at least one guide groove in the top of the work surface. The groove(s) are substantially parallel to the slot. The saw blade is mounted on a blade arbor so that it partially extends through the slot in the work surface. The blade arbor is part of a motor assembly mounted to a cradle under the work surface.
The spindles that support the cradle in most modem table saws are pivotally is mounted between a pair of trunnions attached to the bottom of the work surface. One trunnion is fastened toward the front of the work surface, while the other trunnion is fastened toward the rear of the work surface. The trunnions allow the cradle to be tilted relative to the work surface by means of a hand crank. The operator is able by use of the crank, to produce cuts that are not necessarily at a right angle to the work surface. Also, modern table saws allow the operator to raise or lower the blade within the slot by means of another hand crank.
It is crucial that the blade arbor be at a substantial right angle to the guide groove in the work surface. In other words, the saw blade must be substantially parallel with the guide groove for accurate cutting. The orientation of the blade arbor to the guide groove is characterized as the heel of the table saw blade. Unfortunately, known means of blade heel adjustment are generally unsatisfactory. Each trunnion is typically fastened to the bottom of the work surface by stationary bolts that extend through oversized or slotted bolt holes in the trunnion. This enables one trunnion to be moved laterally a small amount relative to the other trunnion to correct misalignment of the blade arbor relative to the guide groove in the work surface when necessary. Thus, with known table saws, if the cutting blade is not parallel with the guide groove the bolts that fasten one trunnion to the supporting table are loosened. The trunnion and the cradle that it supports are then be forced or pried to change the heel of the saw blade, often using crude means such as striking the trunnion with a hammer.
Another known means of adjusting the heel of the saw blade involves the use of set screws placed on either side of the stationary bolts. The set screws may be loosened or tightened to move the trunnion and cradle. This form of adjustment requires expensive secondary machining to the trunnion, not to mention involved execution of the adjustment procedure.
The adjustment device proposed according to the present invention addresses these and other difficulties when adjusting a trunnion. In particular, the present invention provides an inexpensive and direct solution to adjusting the heel of a saw blade relative to the guide grooves on the work surface.
In accordance with aspects of the present invention, a table saw includes a work support table that defines a blade slot therethrough and at least one guide groove oriented generally parallel to the slot. A pair of trunnions are attached to the lower surface of the work support table, with at least one of the trunnions defining an adjustment opening having opposing sides. A cradle assembly has a blade mounted therein driven by a motor, and it is supported by the trunnions such that at least a portion of the blade extends through the slot in the work support surface. An adjustment member is received by the adjustment opening in the trunnion and is rotatably attached to the lower surface of the work support table. Rotation of the adjustment member causes the adjustment member to contact one of the opposing sides of the adjustment opening, thus moving the trunnion to adjust the position of the blade relative to the guide groove. This allows a user of the table saw to more easily position the blade parallel to the guide groove to insure proper operation of the table saw.
In exemplary embodiments of the invention, the adjustment member includes a generally cylindrical adjustment end that defines an off-center bore extending therethrough to form an eccentric. A second end that defines a bolt end or an adjustment handle is coupled to the eccentric to allow a user to easily rotate the eccentric adjustment end. The adjustment opening may define a variety of shapes; for example, the opening may be oval-shaped or U-shaped.